In order to capitalize on the advantageous features of peroxygen bleaches, considerable industrial activity has centered around the search for means to increase their bleaching effectiveness at reduced temperatures, particularly at temperatures of about 60.degree. C. and lower. A variety of compositions have been disclosed in the art which employ a peroxygen bleaching compound in combination with one or more "activator" compounds which are said to promote or otherwise augment the bleaching power of the peroxygen compound, especially at lower temperatures.
U.S. Pat. No. 2,955,905, Davies, et al., issued Oct. 11, 1960, discloses bleaching compositions containing hydrogen peroxide or inorganic persalts and organic carboxylic esters having a titer in the peracid formation of not less than 0.1 N sodium thiosulphate. The esters, which include isopropenyl acetate and .DELTA.'-cyclohexenyl acetate, are said to deliver improved bleaching at temperatures in the range of 50.degree.-60.degree. C.
U.S. Pat. No. 3,816,324, Fine, et al., issued June 11, 1974, describes dry bleaching compositions containing hydrogen peroxide releasing compounds and bleach activators which include various N-acyl azoles. Examples 12 and 13 disclose sodium perborate combined with N-octanoyl imidazole and N-palmitoyl imidazole, respectively. The compositions are said to be useful at relatively low water temperatures.
U.S. Pat. No. 3,640,874, Gray, issued Feb. 8, 1972, describes activated peroxide bleaches containing various N-benzoylimidazole compounds.
Belgian Pat. Nos. 858,048 and 858,049, both published Feb. 24, 1978, describe certain alpha-acyloxy(N,N')-polyacyl malonamide compounds said to be effective activators for peroxygen bleaches at low temperatures.
U.S. Pat. No. 3,822,114, Montgomery, issued July 2, 1974, relates to the use of aldehydes or ketones to activate certain peroxygen bleaching compounds, but not including those which release hydrogen peroxide in aqueous solution.
U.S. Pat. No. 3,130,165, Brocklehurst, issued Apr. 21, 1964, discloses activated bleaching compositions containing inorganic peroxygen compounds and esters of phenols or substituted phenols with an alpha-chlorinated lower aliphatic carboxylic acid, e.g., chloroacetic acid or alpha-chloropropionic acid.